Protest leader Suthep Thaugsuban, seen here on January 25, says a relocation of protest sites is not "a retreat but an adjustment".

Reuters: Damir Sagolj

Thailand has held elections in five provinces where voting was disrupted in last month's poll by anti-government protesters trying to unseat Prime Minister Yingluck Shinawatra.

There were no reports of violence at Sunday's vote, although gunfire and at least two explosions have raised tension in Bangkok before the Feb 2 polls.

Election re-runs planned for April in other provinces have been suspended pending a court decision on procedures.

Voting was disrupted in 18 per cent of constituencies, 69 out of 375 nationwide, the Election Commission said, affecting 18 of 77 provinces.

The demonstrators, who have blocked intersections in the capital for weeks, say Prime Minister Yingluck must resign and make way for an appointed "people's council" to overhaul a political system they say has been taken hostage by her billionaire brother and former premier, Thaksin Shinawatra.

The election is almost certain to return Ms Yingluck to power, thanks to her support base in the largely rural north and northeast, a result the opposition will never accept.

The result cannot change the dysfunctional status quo in a country popular among tourists and investors yet blighted by eight years of polarisation and turmoil, pitting the Bangkok-based middle class and royalist establishment against the mostly poor, rural supporters of the Shinawatra family.

Protests abandoned in Bangkok

The anti-government protesters gathered in central Lumpini Park, where hundreds already sleep in tents alongside boating lakes and under trees, after protest leader Suthep Thaugsuban said they would abandon other sites in the city.

Posters saying "Get out!" and "Stop cheating farmers!", a reference to a failed rice subsidy scheme, blew in the dust past abandoned Suthep cut-outs as traffic began to ease its way through the intersection on the edge of the Silom financial district.

Another protest site was dismantled, with stages, huge screens, giant speakers and amplifiers, tents, stalls and mobile toilets cleared away overnight, but the elevated highway along the south side of Lumpini Park was still blocked by tyres and sandbags.

About 20 protesters blew whistles at a polling station in Petchburi province, southwest of the capital, but did nothing to block voting.

"They came to show symbolic protest and they have already gone," he said, not giving details of voter turnout.

"Generally, polls are running smoothly."

Mr Suthep, who has proposed talks with Ms Yingluck, did not mention the voting in an address at the new stage at Lumpini, but said he was confident the government will want to negotiate while he continues to attack businesses of the Shinawatra family, a tactic introduced last month.

"I'm sure that he government will send representatives to ask for negotiations with us," he said.

Protest numbers have dwindled amid attacks on various camps with grenades and guns.

Three people were killed when a grenade was thrown into a busy shopping area near one camp last Sunday.

In total, 20 people have been killed in protest-related violence in Bangkok since November 30 and three in the eastern province of Trat.